SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0efe37a9309a9b1fbcba98900f75440e949e50cf3cc685c349be626092421fd8' 
  AND token = 'S559XSLbKYZMueKisMUiXx8LrvBaVJfSWZFrwDVgNB0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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