SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6e429eec4097faac75d454a2184c7efa3ade335ed09a773719b0262a04b2384' 
  AND token = 'mdciyhWXUoxHyz2G2RoVBzLuj0W+8rfn7wcBboWOGkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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