SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ca1a79300f852921de3fd61c07015f217aa1af86c1aed966224c2a52eadb2ea' 
  AND token = 'R2qQwud+oVS5ETG2aBzFHiL36XhaB9hsdgMMLSmA7hM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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