SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc573cda2faf316cc6e88a981582a7bb93241eca32948d253b58ce7cd76ce936' 
  AND token = 'PLj82lQ18nWL5QJ1Oh/mPz2qqxFVwYCGkIUFmG9lCkA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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