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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd93ca8471cb95a4b4af2a2f19abb4a4f7ac9292517df00e50757fee896fed381' 
  AND token = '1qLDavJ8beHJ1saqzoITvbEr3eKy6GMUgcryfitVC9M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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