SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bf8295d81fead0f70274f925daad595b26b7e5cd2f09c55f97bc1dd854f0caf9' 
  AND token = 'IC8v+Hidj8ffawdihcZ/0+QdGpSv9yNxrgq30xCpk50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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