SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8548628566693082da115dcdc52e3c45b198394cba0febe50fca20dc8fe203a6' 
  AND token = '5H+NvuWe3Pnf8XTE3VCmzo0P/sPyyOhinI6jWOF7Mbk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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