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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8a86b696caaef5c002e2a3ab695659ef302ac3627b8612c2c3de4a9e1bbe9551' 
  AND token = 'FkYDuKbGBZlMj4Gg70rNHsrGpB4Wt5gUfuGk/Mj+xcQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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