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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c961ebfe9ade45be53730e91d3204d2d2cc5857e9c628cb2a95b1e880a5a3cd9' 
  AND token = 'test2nZ2BMN4qkqgcPTx5T3EJwZOqE4+ldyzdtEntvA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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