SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'edc51d8ffdbe6e13223e673c682ef2ba538ad967a895ebe5bbc333768e84c9e6' 
  AND token = '74yRE9uAMu1N/JD/Zprq1Czh++1qWWusQsjdMfNBlh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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