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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a03e58243ceeda1b30d5ba7cf25804a0439b44b7f29bb88d16f3ec0ec6f49f4' 
  AND token = 'd9HjczRVSiuKgkx0SiBJ8oqTcXTD+j0H+1Fbiu+AUYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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