SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '08b23ae6116326c71713b67d4d421726143cd15d5f1327491e807bdec754b659' 
  AND token = 'gNUvTGn6GaQ825arPgg9SVLsBrC+LeBuv7YHHks/bV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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