SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8373602798c1ec9fc471c609f0de81bae774f5b1f7fff7b5b1c781e4b7b23d2' 
  AND token = '6hNPANtBURFhNiWDWAvilCQF9SHwJnKRtrvqDggZUdw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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