SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '102b1cee217e2b68ffe33ce451d9a1a1d6d4b91630d4fdf8942ae009009eb67c' 
  AND token = 'die7JNDGvR1AEmVMwfjELhtw8hY/V+SZkBMiz2YKdVM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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