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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4f9b553ade1e138ce4784f5b53adf400690cf2eb29eeaa492c27372d4dc58ad' 
  AND token = 'uC9GkS824X3Slg5nHKv7ZGq9hqZaC2LrGdOgKlJ7fHQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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