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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3af6879efa3e7d4971457dd5798f67d78a46552a4a4bc41fadd6cd395bb06c91' 
  AND token = '3TUwsQhRKdFH0Tm+A3xWZrWuTYSlNTPzdbq43rr1gSc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00011

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}