SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d35fb6d0c31dee51e64f8e6bbc13ad8995c9fd6f48640b56530dd7cd930bd77' 
  AND token = 'g21VVjmmChQaF0lXx1k53oWqvLgTMHpITFMXmRHVoS8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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