SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0dc23a1e22d95c979720602cdb197545ffea268d8434b6f8e6a5af83af2700d3' 
  AND token = 'ppVMHMLHge+UTnMtSJDQmyvWJfUe7tC2mTXr6UYA3FU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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