SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9b867e69ffb2c6bbc0978b7542aa3d3eb58af55d6aa2b75793067e6d188bdbd' 
  AND token = '/KMJjbvNpEwsC9T4B2Mf0D2wujrmrYSxvcpJKgUtf8c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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