SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e0422b111b9f9603354185718c6ddf28b73d2cc866fd9faaaf28a1ac7cce272' 
  AND token = 'UHI/klEnJIow4abEUN6C3a1nd5YLgid0hwCSFdXQXBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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