SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48923d261432f566bd1b12643228a1f036b0e6bd346c7fbcd530d0450f404946' 
  AND token = 'yEsrhyfuAsLR5Fw559C+S/oBYb7aMY1K8Jt0qtosw74=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}