SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'ab8b8374d84eb78678c7349657355de1d302b1e2659b84363a42083f32e5203a' 
  AND token = 'dlztb/nO3LePJb+hZLgYLLVAiUWHzKZOmoOsM98z6uM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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