SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5887643fad893cd51c3634c61247772e2b30f59ccfc57ece707dfb52eec27451' 
  AND token = 'cZzUbwECOevnfx00aaG12yvLFnNeePLs+bVPWjeiA/s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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