SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9e275ab858f2cdda35829ca49f35e10d0b0d58ace07da19a8f781e8a651422c1' 
  AND token = 'wFazJiBLBJnzDLpQB64GL+mVpiqqDdKaEcuWLFSb/D4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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