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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78e1ee1d7cfb1fc4459cf03de2092d53d1e3ad31f54adfbc445b63d44d67f7ba' 
  AND token = 'pkiHTbQElKj5O+7HMzkLo60/sCVOEXPXm2iqehldujE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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