SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46528518b1d4d1b90e1727562d2af1055f2c7a5f6dbe601e49c1c8944ad1be6b' 
  AND token = 'WuauPUc12LnU99HpPjnO+50zr4z7WUrd14MpovNPmBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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