SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f7e2b27c274427416a08fdbc21eeb3e2e907dc87519a33f2737b034985e0d7c' 
  AND token = 'LMdFaSB1NigBp/sWcwJ98xRs8zcHXV3ai9oelEhE9FM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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