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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e51ee93fa7c1bd97a05de5bda81757d44b5ee018ed2235c318aa0e72039d68ea' 
  AND token = 'M3vknQJlUT58cjOUHSz2eOJCVZ7saPItxjINp+d6vXU=' 
  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"
    }
  }
}