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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '741308555a7f02dc8f2e6dbca73f4c7ecf5351bdc5d3f92c4f3796ccd1796ba7' 
  AND token = 'xW3wXqe4PvsQXEq9vx5WcnSVPo8c+/ETCsKIbOpqppk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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