SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91c6064889bcc04007db23ed3efacff647ca5c545d52acb737ca48a6504e32f8' 
  AND token = 'e5FhsmBldvVOsoo2EjTM7VjZN2GhMCrmsi+QaljuStI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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