SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a51c5bd6fc7eab73439a6f95630040bccacf173c67c2b003d3128d38b1b7d6aa' 
  AND token = 'jI/YWwFPZIvzALkMlavC2c5/tj56PhTM4bQjqoFFEMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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