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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e5e321ef983f6e86261510175a4ac8bf3d864aae455880d0e1aed9727b16577' 
  AND token = '4XTmREi7hr5k2YZ7tuUQcHq40LVHHM1zrT27h++gpPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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