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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8bbc3e77a21841aacdc7125ba4508e6e817765681ab7d16b48b04eeb4fe9bbb' 
  AND token = 'lmPqETwl6+OQBH2DLIjC/FaO8CGyFY9At3AL6G/Cy70=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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