SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd90b52e5c4bcde17372c51463395ade0a2f6fed4611d8f7a0455ba38a6678b78' 
  AND token = '0zyLA7/AI1IPFIdOmz6KZnrEv80GdPKNCEGtcJXfjrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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