SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66efc9be15a670bda04a29232c6a86549b36aad26adeba590b598e08d47eb7ac' 
  AND token = 'zdxPxncWjOGqAGnFfqRq2U/8QWeghYOsckyaoyvG9Qg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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