SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '903ea1cc9b6e96f56ba94aacf30133757f8b9e08f3548e99017d4352843251e4' 
  AND token = 'aKos+bodDphF3UCScd2PoFNbElEyhkPFMp58fJQx+5U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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