SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9c3969938c689bc1606b3a1d6fd9c8afdd4c2ce7f43b3acffc0c725e3eb756b' 
  AND token = 'H57oOKZVpGPU8N3MVrzgVPTQWCVIwWKEF2evlkjRqeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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