SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '203e1183f60367fd6ed5b65bbd6348a0843354fefd1bcecb0bd9a22fdae73f26' 
  AND token = 'OU19UBd5fmiGlvElOer+7eOWnMSrbe0uMOObwxf39Hs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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