SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3bcbaada7d9dd05de9745465b259679f9de3a966bfdf6465f227a80bcdd8380' 
  AND token = 'nQhDPWMR9M5TdyEdiDwqooqfmMMJBezOXHIcsB4/mRk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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