SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '510075ae9dd19863c87f292e21b46433b0f22ff392f60c7a8a9c5901b3d76f06' 
  AND token = '+5WzDjU2jsXBOBzQmr0HqGutyD1qs/C1oCrLjW8z7Z4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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