SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd81d130503ecf9e23c9ff85def249e4b68944bd8fe34d2a69e93111579a9c451' 
  AND token = 'EWxaMms9kmcqwL1jOCLOjP7ZCT/MulzHxkIhoLAGolE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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