SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86fe8193dd35669cfb8951d2547d1f674629503e0b0b107d3e40aab88d19d7a9' 
  AND token = 'lvHxPH8hPP4OTEs8ozx1YB7i/woVzHPCquf5YzK38h8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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