SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f79b0bf8e29a0b4e34584bd116622b7e7999fd87e989e4a0e506ac5d37cbdc2b' 
  AND token = 'VcaUBV0U2CFMkRVZjpwJbMzKNp/9035yj8OQKXQRh30=' 
  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"
    }
  }
}