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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1a97bd6be9d3ee76f4146de3d31d7e88c6d6cf14585d1ffeb41bdb1d3c13b1f2' 
  AND token = 'MYqJhIWLLzGFC2mAMzJz/9siZVcZeunXUU7csgThumo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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