SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec715fe57f7fb8d53d084de917d4dea8340167a4d162d52beef7c7de9266166a' 
  AND token = 'LzRLDYEXjDFbhhUJpCNRoDF6exRn3fRPwQ0akdXj998=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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