SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7b635f2fece5acf3456d80ea68338f83390afc907c2f9b6edfe669ac0d9301c' 
  AND token = '+Zuvn2S6nGA0ZkDo1tonYd3xvmFO4iSJskYp5wIctm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}