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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'dfec900524397247434824ae57c0191e5192b1f073be9c0552b9eec97f2e5031' 
  AND token = 'e6rfY0vIynTodJXSUkbDlgAZGxlFH1T37qXhAuERs58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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