SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4dcb9fab6d847dbf7a3f5396c004e518ea633d49b62b17b8017cdf624a84883b' 
  AND token = 'S6/qVg3i541VaGCBx/MVIP2Gb/RkJIRhzCeJpA8lLXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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