SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '49804fdaec6da24417872c2ca54b3c57d45a69badba219f6550e2c5ad8edd90b' 
  AND token = 'EU+LpejTrn1Q9083SDFzL4I+VmS/2nbIpv0JBIhoGzo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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