SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0b3620d28503f40b9056b07e83fcaaa1298d3384bf4e839e34801825494ec1d3' 
  AND token = 'npQHX32beXdchAUscMsvnxwWxM2V1FPvyr+tB3ZHhpQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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