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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5b776efa1cb399c7e201c70bb5f3bc2dfa61b08b6b0a8749997f69aa5e4a72d' 
  AND token = '8yn6NM/We3nYp/yVwQ9HW1B3x1darkpTSjsTRZnfG3Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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