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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50cfc1b3ec92c00ba3ff83d7b2eb7f45823491b8dfe4c0d5d933b9aa67b2020f' 
  AND token = 'K0GcxaWeIVZfmdKDjMGHtU+z4bOFff8lM1Ue4nP32eE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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