SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e809692b7453cf2ff37e477a25e4d21b796782e99e712f0fa4d662a71467095' 
  AND token = 'C3DEcJrvz4ZKMYSs7JHvBntALXsm5qPplbsn0njzCOE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}