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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a331f6807b1b2e3759a54ebc837b08323a6266b94fdab690b0329d300bd5591c' 
  AND token = 'HY5MJEsOjZtBWROWy5D1NIrtLYoFL6xJ82KWkLFjPYk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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