SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08c6bb4ee6624162c791edbda616d2521de6ec36273203c7f5057db727d6a1ac' 
  AND token = 'MtsBVppmn3rb1u+IfzBRgv4JkmF7YoRXrCLbzizFYVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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