SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae7320cba6027d52967ca0c8743b19b3e87954ee3e7ece132d97e7f0d5cf5511' 
  AND token = 'xM14oIPVHHFxD8YRmkw7kZL1IMbS8W5fdBMYLQ21Nac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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