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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6663520b9c181a7ca89d81cea09ad8d12c74f9f4854ec2e31dd4d4d0335f29c7' 
  AND token = 'H3kQVvKkls7YHd7h+Lhnla3mf6GO6yUHG/RneGaoZn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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