SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '64581774e1c77e2193ab523765f629f6ad99ca6038c768b952e58fadff921cdd' 
  AND token = '8LeJ5dmMnr7rEngLEEnGXchPOEpk86fR0x6EXaOQ+2M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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