SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15777e4c189054668d20012eff72daa5edd32bbb3efd7550eb917e0e7f5934be' 
  AND token = '6mtXIlh0FfSUEPD2fo9Fi+hieO7s1LH/JWHJeh7TW5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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