SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '686acc126bfd5db8149cbcfdc3e5226a5f6f865a1355bc683f640a74f91f16b4' 
  AND token = 'vC369Ev4fXrs6/uVVebl6aLgRB94an8v6qNcLEwzItE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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