SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15fda0deb343fb62cd65f579628783242efd7acd4cce9e36989f4f8565a3275c' 
  AND token = 'Mv+ZK72PrIQm7ThBVulCSgzhJDT2HTYF8kot/3+cN4Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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