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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'df571e777b0368b51a7eee226c80c14fb98af4301819a8b550efa2cf884c9abe' 
  AND token = 'qIhid5ZnKSyR8cTeXZ3D6DtiRRLGpM/Y7A6K7RSIj/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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