SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b4219667ded13b7566920fad47a703cdbbfbc885589a0e5063164e1fe238431' 
  AND token = 'E+OfSo6nrWqQwLFCzj3MIP0GwvuMF2GFxBSx/2WimlQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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