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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99ca6bc448ec8d0acaf0508cb468769f289ffd7f93852ef6e584ad0bd913a753' 
  AND token = '9Lbtrf8jyUPAmsSauRS8ZDjMpqlbXk7/YpSCuBAB46Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}