SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5341012bafd3bbde86bbc4f90a5b64dce238d7900e78d0c163350a78467335eb' 
  AND token = 'zaJQHWiRci+RmMzGMiyYNEshNCqwMhXCTnuS++d15mE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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