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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3ec8e32947843e0d6d1dc461cbef5e7fca772cf922623e0b44ebd1b646d4ff2' 
  AND token = 'LE+2eTYYu7+30+LULZ7TTLRnxOJ1y+Q7uid2EPvIzJI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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