SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dbec0b89765f559c48af3123047182f01e624cd4bf66abb0a02046432208af3' 
  AND token = 'vj+qFFRMIh/ebd7aDWPIOO3phH/eNGxXDHdITpAUISs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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