SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8d321ea8d7a39201b6f8a25c20d94f90bda73c3f8508c823e0e87a0f356e167' 
  AND token = 'QctJPsCCnKuyDimHAMyUXFVfcqX1Qgv3gjRz4lKteAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}