SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b356e661df00b74c0eddd107673035639e2092bdce158ca23f30e88e21d6d96e' 
  AND token = 'P1komSoVqmJFCPMjPSF/V98Hxp3PAFS0SwPWxUxLL68=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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