SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eebed4e07423cb548b79018c33eadd52247042b429de30f6f6a376530e560c79' 
  AND token = 'pS4WiztE32CTryv/G1bVFhCL9SU+pXvSMDjCN8LqYPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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