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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6e401357a3aaea259b35247a1cdee64563a1d8c8a492e525819b8c0a6c5aba2' 
  AND token = 'crhw6K0UG3wwci59GB6wmn+pN+KXQik1o5mwpf5ESuc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}