SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18514c0f0c4c66a96487575459b4bd97f58eb2864c27e2cdcc2f1564034bbda5' 
  AND token = '35GizPt5TXqtneoglDBVy81y98DkpGo2M2ISMmOexNY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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