SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c728aa32db8655e74908afaf28633e822f909ff71e324ba3498f46792300012' 
  AND token = 'r5faglEb/3965tteTXpm6HtaE2CmspkN+62xPc5pvlc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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