SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'add5c8c198c43c962d54bdd9110957f06619ab77fba90937b414a0b2684da84b' 
  AND token = '7cY+qfLj5NTovaCRAyduxPjzjxXT8vDieCXT/wdZh+I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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