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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81b4967fc6cda50573e9b94bce38ca7bc6ef34f3130e9957c3faab8c879a086c' 
  AND token = 'g2OpEgCg3noP+IxKN0w3MDehmj8i0WO4PtPFJ0c+qzg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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