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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c834fc16be69b98b5bb7c1ef1c1b71b3da2609c7a98dcc2b3e06f1125adf7a4' 
  AND token = 'yUEZMZ6smxLMahwTVWsLycQgHyWwV8W9afs7vWDcUwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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