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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc3c0a83c6b4f1b490cced265137a7972c142ab79174f8a7b2dc080b76b16ce2' 
  AND token = 'bc0AvgZzplHH4JB5mQrzRhbF8ZDbW/eR8j4hg+Y036A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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