SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8a11d52c3d4395b1a7b364985b3a6396f9c0c258feb68a781ebb805f95bfc48' 
  AND token = 'tMRN7tGQWcmILMdJlLnQQU1y80wwrxc9SCqTMVeuHU4=' 
  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"
    }
  }
}