SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e18e35da527636a403e65f728684b077beb070c841a65b7d000adbbd6cd640d2' 
  AND token = 'WpiYonhGF5yoYPeBVYJh+NeLDeIEmajtGw1C10GS9LY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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