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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2fd1ef258bdb72bcdcc85e2c7ccd0404e956d6955dc1d30b45a4884d0ab7fe12' 
  AND token = 'ZXDarHDze0mVeTqZ04O7EB4lK+JiLLMCYeHLINoqM/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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