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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3f36ebd9fae23f9517b0e48e1834c2e1b6ea2bdfba11bc015eaadf3d6505e74' 
  AND token = 'rzm4qo/6rUsXos4GHQyz0BKsKjkLjwpn5pdgK6u21KQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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