SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '876896608ebfc52c62e46448b71aacc5f4680c204fad8aaf131ff298abc962bc' 
  AND token = 'UpHCbzyFY1xCvX+opyLVNG3yA738+eP33UJ/qhikj2A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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