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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'dd8bfac56c5e4bf314d24d34a25a5c50ac967b13cf3cb3e27f53a6df55cc1274' 
  AND token = 'lE7cRifVifAG2g5GHCrPTRKLB5wCzrErNq/bRGIkXl8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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