SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '706c3795427f916b3081d1bb96e1bd5a3b0ac874fddd99ba225fac4ded5d7742' 
  AND token = '2JErUK5GlS+z/MEyFB5bGCMeErOXxrZkTR1pm+aPjIM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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