SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34c8ae3da42716e21bb76de71a0146cbea9b32f182f4a75af0c8d61576963517' 
  AND token = 'PZqLZHvAS0RKVx1LO4XmWOZEQ/R1TV0+7VuhVZ3Zzj8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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