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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bec5cfd5d0770b86b401f01143a4f24b39145731c935962c2d288a2e658b862' 
  AND token = 'tebVe8qhkthvQCD28tzMx64KVHZ7MS0hfb84qFQQ78A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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