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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff8c4e3db5f2f4ecb1289aedcda68a029fb7f1c20dfb6fe04145b905eeb7a24b' 
  AND token = 'hikiQwoK7r232YQ1ChC76kTxgOnk1/0U3zrmxfluhR8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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