SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3475ee25a6bc2018942f5500db03cbeae00306f1e73bc91e9e46d4919eb3ce2b' 
  AND token = '1GLvGHUArdlpDqRGygGCnZtJEyG2hlE2GaCRIi1GGE4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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