SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bcf60c6832c1bb53cdd4881fde36932b16271f0e35129b4f1870081fea45a376' 
  AND token = 'I+CfP3NojY2ADJAWwVr99tvtMe0hKHGK6+TIc12wlcE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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