SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3428eb0d54d874ba84889b58ced7b6a1c00dbf2575b00b95636cd8f33f539ada' 
  AND token = 'zExMnvTII227pnhAr+Uzfzol67j3BLFlAfDEBu2B1vQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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