SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c126809fc18b0a6f7a6f5dd05034296d3483f034bdd888d5a81ff503c35b2bf9' 
  AND token = 'h+P9nMtqFsG4FGXdBT4xSvV0H96SJJVaCOh7AX4mKCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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