SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5e20d9f0c1dc42b39da449b9005ef559ee30115688dcff9369d3afd5fb804f37' 
  AND token = 'DklbUBtgsn1U0gMH5ZmNmDOA1M1HxDOWN515a7ZVeEM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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